In order to manufacture a semiconductor device, various kinds of processing apparatuses are used for performing processes such as oxidation, diffusion, Chemical Vapor Deposition (CVD) or the like onto a substrate, e.g., a semiconductor wafer. For example, there is known a vertical-type heat treatment apparatus which is capable of performing a heat treatment on a plurality of sheets of substrates to be processed at a time.
Such heat treatment apparatus includes a processing vessel, a boat, an elevation mechanism, and a transfer mechanism. The boat serves as a substrate holding unit that holds a plurality of substrates with a predetermined interval therebetween in a vertical direction, which are loaded into/unloaded from the processing vessel. The elevation mechanism is disposed in a loading area formed below the processing vessel. The elevation mechanism serves to ascend and descend a lid for opening/closing an opening of the processing vessel, with the boat being mounted on the lid, such that the boat can be moved upward and downward between the processing vessel and the loading area. The transfer mechanism serves to transfer the plurality of substrates between the boat in the loading area and a receiving vessel receiving the plurality of substrates therein.
There is an example of a heat treatment apparatus in which a processing vessel is partitioned into a plurality of zones in a longitudinal direction, and similarly, a heater is partitioned into a plurality of zones, each zone being provided with one or more temperature detection elements composed of, e.g., a thermocouple. For example, an inner temperature detection element is disposed corresponding to each zone inside of the processing vessel, and an outer temperature detection element is disposed corresponding to each zone outside of the processing vessel.
However, such a heat treatment apparatus suffers from the following drawbacks.
In a heat treatment operation of the heat treatment apparatus, when a temperature detection element disposed in a certain zone (or unit region) is broken, a detection value of the broken temperature detection element is switched to a calculation value, which is calculated from an actual sampling measurement value based on a dynamic model so that a temperature control is achieved. In this configuration, the dynamic model is derived for every unit region. Thus, this fails to precisely calculate the temperature of the broken temperature detection element since it does not take into account the effect of the temperatures of other unit regions on the temperature of the certain unit region.
Additionally, it has been proposed that when one of the inner and outer temperature detection elements is broken, the unbroken temperature detection element can be used as a temperature detection element for temperature control instead of the broken temperature detection element. However, such switching may cause a fluctuation in the temperature of a substrate. Particularly, when increasing or decreasing the temperature of the substrate, the switching operation that switches to one of the inner and outer temperature detection elements as the temperature detection element for temperature control may cause a large fluctuation in the temperature of the substrate.
Such fluctuation may occur not only when the substrates are held in a vertical direction, but also when the substrates are held in other directions with a predetermined interval. In addition, the fluctuation may occur not only when substrates are subjected to heat treatment, but also when other various kinds of objects to be heated are subjected to heat treatment.